Question: Simplify the following expression: $y = \dfrac{5z}{7} - \dfrac{z}{2}$
Explanation: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $7$ and $2$ $\lcm(7, 2) = 14$ $ y = \dfrac{2}{2} \cdot \dfrac{5z}{7} - \dfrac{7}{7} \cdot \dfrac{z}{2} $ $y = \dfrac{10z}{14} - \dfrac{7z}{14}$ $y = \dfrac{10z -7z}{14}$ $y = \dfrac{3z}{14}$